Bulletproof: Investors are waking up to the fact that a new generation of tech CEOs, including Groupon’s Andrew Mason (left) and Zynga’s Mark Pincus, have put in place protections that make them tough to fire. Photo: REUTERS

Armed with a special class of voting stock that gives them added power, today’s tech CEOs — including Andrew Mason of Groupon, Mark Pincus of Zynga and Mark Zuckerberg of Facebook— are virtually bulletproof when it comes to their critics.

Even the most vulnerable CEOs based on poor share performance are proving immune to investor discontent.

Take Groupon CEO Mason. Investors sent shares down as much as 10 percent yesterday when they learned that he was staying on despite an 85 percent plunge in the stock price since the company went public a year ago.

Signs that at least one director was lobbying for change at a regular board meeting on Thursday raised hopes that Mason would be replaced by a more seasoned exec.

Then reality set in, sending the shares down 8.7 percent, to close at $4.14 yesterday.

“Mason will be almost impossible to remove despite his terrible performance,” said Sam Hamadeh, CEO of PrivCo, an investment research firm.

Corporate governance experts said Groupon’s ownership structure solidifies power in the hands of Mason and his co-founders, Eric Lefkofsky and Brad Keywell.

The three own less than half of Zynga’s shares, but because they have super-voting powers, they control 50 percent of the votes.

That type of corporate structure hass been put in place by a number of Groupon’s peers to ensure that founders keep power long after their startups go public.

Zynga CEO Pincus also holds a special class of shares. He, too, has come under fire for his management as Zynga struggles to migrate its popular desktop games to mobile devices.

Yesterday, Zynga Vice President Roy Sehgal and Steve Schreck, a general manager, became the latest execs to head for the door in the wake of Zynga’s sagging stock price.

Perhaps no one has more dictatorial power than Facebook’s Zuckerberg, whose undisputed control over the company drew criticism even before it went public in May.

At Groupon, Mason defended his position, saying he remained the right person to lead the company. “If I ever thought I wasn’t the right guy for the job, I would fire myself,” he told Business Insider’s Ignition conference in New York.

Ultimately, it seems Mason and his partners are the only ones who can force change.

The tech world is used to running up against founders who won’t relinquish power. Microsoft’s bid to buy Yahoo! for $45 billion — more than twice what the company is worth today — was blocked by Yahoo! co-founder Jerry Yang, much to the dismay of shareholders. Still, Yang’s grip wasn’t nearly as tight as what the newest tech CEOs have engineered.